I have successfully created dynamic text fields through actionscript, and changed their color, boldness, margins, size etc. but when I try to embed the font it isnt working, any idea why?

All I am using is the following code, which according to its refence should work.

myTextField.embedFonts = true;

I have also tried it as part of a text format object but it hasnt worked; like so:

myFormat = new TextFormat();
myFormat.embedFonts = true;

Has anyone got suggestions, or have they been having a simialr problem?